Pneumatic starting system for diesel engines

ABSTRACT

A pair of normally open, air-actuated valves supplied from a common pressure source and acting respectively as a line valve and a pilot valve, the latter for controlling with associated time delays closing and reopening of the line valve, for automatically purging a diesel engine of any liquid condensate by applying operating air to the engine&#39;&#39;s air starter motor in two separate stages, one brief and the other extended.

Bredlow PNEUMATIC STARTING SYSTEM FGR [56] References Cited DIESEL ENGINES UNITED STATES PATENTS 3,104,659 9/1963 Smith ..l23/l79 F Inventor: Harvey F. Bredlow, Salem, Va. Examiner-A1 Lawrence Smith An W'l M 111' Assignee: Graham-White Sales Corporation, Salem, Omey l met cc m 57 ABSTRACT F! d: F b. 16, 1970 l e e A pair of normally open, alt-actuated valves supplled from a Appl. No.: 11,754 common pressure source and acting respectively as a line valve and a pilot valve, the latter for controlling with asu.s. c1 ..123/179 F, 60/14 91/53 time delays 05mg and "Waning 0f the valve,

137/613 251/16 251/52 for automatically purging a diesel engine of any liquid conden- Int. Cl ..F02n 7/08, Fl6k 31 12 sate y pp y g Operating air to the engine air Starter motor Field of Search 123/179; 91/53; 60/14 B, 16, in two Separate g n brief n the other extended- 8 Claims, 6 Drawmg Figures l5 2 6 /5 2/ 3/ -27 2 2 V j I] 22 I j [6 5 I a a 5 /.9 2B z 26 I J f 5 7 [B DIESEL /a T 7 MOTOR 1 AIR PRESSURE SOURCE PATENTEDJUN 5 I972 3, 667. 442

Inventor:

Harvey E Bredlow Maia/UM his Attorney 1 PNEUMATIC STARTING SYSTEM FOR DIESEL ENGINES BACKGROUND OF THE INVENTION As recognized in McCreary'US. Pat. No. 3,342,170, water and other liquids formed by condensation in the cylinders of diesel engines during idle periods can cause extensive damage if not purged or scavenged at the outset of the next starting operation, and in that patent this is accomplished by providing special valving within the engine. Other patents, such as Jenny, US. Pat. No. 2,886,947, Adams et al., US. Pat. No. 2,953,127 and Smith, US. Pat. No. 3,104,659, disclose pneumatic starting systems for diesel engines which, once actuated, act more or less automatically for solving particular problems. However, in none of these patents is the disclosed pneumatic system either designed for or capableof solving the problem with which McCreary was concerned. It is to the automatic solution by pneumatic starting systems of the problem recognized by McCreary that the present invention is particularly directed.

SUMMARY OF THE INVENTION The primary object of the present invention is to provide an improved pneumatic starting system for a diesel engine, which, by automatically applying operating air to the engines air starter motor in two separate stages, the first brief and the second extended, prevents damage to the engine from liquid condensed in its cylinders by purging the liquid condensate at the outset of the starting operation. 1 Another object of the invention is to provide a pneumatic starting system for diesel engines, wherein a pair of normally open, fluid-actuated valves, one acting as a line valve and the other, with associated time delays, as a pilot valve for the linevalve, are responsible for the automatic two-stage application of operating air to the starter motor.

Other objects and features of the invention will appear hereinafter in detailed description, be particularly pointed out in the appended claims and be illustrated in the accompanying drawings, in which:

FIGURE DESCRIPTION FIG. 1 is a top plan view of a preferred embodiment of a valve assembly for the improved pneumatic starter system, in which the pair of line and pilot valves and associated time delays are incorporated in a single structure;

FIG. 2 is an elevational view of the outlet end of the assembly ofFlG. 1;

FIG. 3 is a vertical sectional view on an enlarged scale, taken along lines 33 of FIG. 1; and

FIGS. 4, 5 and 6 are diagrammatic views of a preferred embodiment of the improved starting system showing the relation of the parts and the directions of flow through the connecting air lines, respectively in the brief first power stage, the interval between the stages and the extended second power stage.

DETAILED DESCRIPTION Referring now in detail to the drawings, in which like reference characters designate like parts, the improved automatic pneumatic starter system of the present invention is particularly designed for purging or scavenging water or other liquid condensate from the cylinders of a diesel engine before the condensate causes damage in starting the engine by an air starter motor.

The improved system, designated as 1, while operable by any suitable compressed gas, will ordinarily be operated by compressed air supplied from a reservoir or other suitable pressure source indicated in FIG. 4. As shown diagrammatically in FIGS. 4-6, the improved system is comprised of a pair of normally open, fluid-actuated valves, one a line or control valve for controlling the supply of operating air from the source through an operating air line 3 to a conventional air starter motor 4 of a diesel engine indicated in FIG. 4 and the other, a pilot valve 5 for controlling closing and reopening of the line valve in a starting operation.

Conveniently having a common housing or casing 6, the line and pilot valves 2 and 5 preferably are identical or counterpart two-way valves having outlet ports alternately conncctable to inlet and exhaust ports and numbered in that sequence 7, 8 and 9 for the line valve and 10, 1 l and 12 for the pilot valve.

For alternately connecting its outlet port 7 or 10 to its inlet port 8 or 11 and exhaust port 9 or 12, each of the valves 2 and 5 has a pair of spaced valve seats, one, 13, between the outlet and the inlet ports and the other, 14,'between the outlet and exhaust ports, and an axially shiftable differential piston 15 having spaced inlet and exhaust operating heads or valve elements 16 and 17, respectively, alternately seatable in the seats. Normally held by a return spring 18, acting on one end, in a position in which the exhaust head 17 is seated in the related seat 14 and the outlet and inlet ports are connected through a valve chamber 19 between the seats, the differential piston 15 suitably has on its other end an actuating head 20 riding in an actuating air or pressure chamber 21 in the housing 6 beyond the valve seats and presenting to compresed air or other gas introduced therebeyond into that chamber through an actuating air port 22 an outer face 23 having an effective area greater than any opposing effective area on the piston to overcome the opposing force of the spring when the areas are subjected to the same pressure.

So constructed, the valves 2 and 5 have their inlet ports or sides 8 and 11 connectable, conveniently through a common inlet line or pipe 24, to the source (not shown) of compressed air or other pressurized gas. Flow of air through the inlet line 24 is controlled by a normally closed starter valve 25, which, since the starter system 1 operates or is activated only during the starting cycle of the diesel engine (not shown), preferably is of a button-actuated or like type that must be held open and closes automatically upon release of the opening force. An actuating air line or passage 26, connecting the actuating air or pressure chamber 21 to the pressure source through the starter valve 25, conveniently branches from the inlet line 24 and a second actuating air line or passage 27 connects the outlet port 10 of the pilot valve 5 to the actuating air port 22 of the line valve 2. The systems remaining air line is a line or passage 28 connecting the outlet port 10 of the line valve 2 either directly to the air starter motor 4 or, as illustrated, through an outlet line or pipe 28 to the actuating side of a suitable, normally closed, fluid-actuated, on-off line valve 29. In addition, the starter system 1 requires an adjustable or variable time delay in each of the actuating air lines 26 and 27 for regulating or controlling the relative times of closing of the valve 2 and 5 under the force of actuating air and the preferred time delays are knob-adjusted needle valves, numbered 30 and 31 for the lines 26 and 27, respectively.

The preferred valve assembly 32 shown in FIGS. 1-3, incorporates in a unitary structure not only the valves 2 and 5, with the former inverted relative to its disposition in FIGS. 4-6, but also the actuating air lines 26 and 27, as inbuilt passages or ways, and has in the housing 6 a main inlet port 33 onto which open the individual inlet ports 8 and 11 of the two valves. Suitably O-n'ng sealed wherever gasketing is necessary, the assembly 32 uses O-rings mounted in the housing at opposite ends of the valve chamber 19 as the seats 13 and 14 and has the inlet and exhaust heads 16 and 17 of the differential piston 15 formed as cylinders or cylindrical pistons, preferably endtapered to facilitate sliding into engagement with their respective O-ring seats without damaging the latter. While having a common main or central body portion 34, the housing 6 has separate caps 35 for the valves 2 and 5 and otherwise is so constructed as to enable either valve and associated parts to be disassembled for inspection and repair or replacement without disturbing the other valve.

In operating the system 1 for starting a diesel engine by the air starter motor 4, the needle valves 30 and 31 will previously have been set or adjusted to delay or retard for predetermined times or intervals after the starting operation has been initiating by opening of the starter valve 25, closing of the inlet sides of the valves 2 and 5 by the force of actuating air on their differential pistons 15. The pilot valve 5 must close after the line valve 2, and the needle valve 30 for the pilot valve therefore will be opened to a lesser extent than the needle valve 31 for the line valve. With the needle valves so relatively adjusted, opening of the starter valve 25 initiates the starting operation by supplying compressed air to the inlet ports 8 and 11 of the valves 2 and 5. Both valves then being open, the applied air will flow through them to their outlet ports 7 and 10. The air from the outlet port 7 of the control valve 2 may flow as operating air directly to the air starter motor 4. However, if, as in the illustrated embodiment, the motor requires more air than can conveniently be supplied through the system, the operating air line 3 will be larger than the inlet line 24 and from the same or a separate pressure source, and the outlet air from the valve 2 will be applied as actuating air through the line 28 to the fluid-actuated valve 29 in the operating air line.

Concurrently with the flow of operating air to the air starter motor, the air applied to the system will flow from the outlet port of the pilot valve 5, through the actuating air line 27 to the pressure chamber 21 of the valve 2, but under the restriction imposed by the partial closing of the needle valve 31. There therefore will be a delay in the build-up of pressure in that pressure chamber and a corresponding delay in the closing of the inlet port 8 of the control valve by its difi'erential piston 15. But when that closing does occur, the air starter motor 4 will be stopped by cutting off its supply of operating air either directly by the valve 2 or by bleeding back through the exhaust port 9 the actuating air previously applied to open the line valve 29. All the while, the pressure of actuating air will be building up in the pressure chamber 21 of the pilot valve 5, but more gradually under the greater restriction imposed by the needle valve 30 in the supply line 26. This pres sure will finally reach the point where it shifts the differential piston in the pilot valve 5 to closed position, whereupon the actuating air previously applied to close the control valve 2, will be bled back through the line 27 and exhausted through the exhaust port 12 of the pilot valve. Thus enabled to reopen,

. the control valve 5 will again supply operating air directly or indirectly to the air starter motor 4 and, as indicated in FIG. 6, the open condition of the control valve and closed condition of the pilot valve will be maintained thereafter until the diesel engine is started. Then, on release of the opening force on the starter valve 25, compressed air in the lines 24 and 26, by bleeding back through that valve, will enable the system to restore itself to its initial or normal condition.

The objective of thethree-cycle sequence, automatically performed by the starting system 1 when the starter valve is opened, is first to crank the diesel engine slowly through a full cycle, then to bring the engine to a dead or full stop and thereafter to crank the engine until it has started. With the inertia required to be overcome in the diesel engine when power is first applied to the air starter motor 4, the cranking at first necessarily will be slow and a delay, usually on the order of one or two seconds, in the closing of the control valve 2 will suffice to enable the engine to purge or scavenge itself of most of the liquid condensate collected in its cylinders while it stood idle. After the ensuing dwell or pause, produced by the condition of the starting system shown in FIG. 5, the cranking will be recommenced, again necessarily slowly at the start, and this second slow cranking, coupled with the first, will ensure the purging or scavenging of any remaining liquid condensate so that the cranking can continue to the starting of the engine without risk of damage thereto. So long as the dwell stage, between the initial, purging or scavening stage and the final cranking stage, is of a duration to ensure that the engine will be brought to a full or dead stop before the final cranking, it

will have performed its function and a delay of some 2 to 5 seconds between the closing and the reopening of the control valve 5 will ordinarily suffice.

From the above detailed description it will be apparent that, as opposed to continuous cranking with but a single possible scavenging stage at the outset, the improved pneumatic starting system of this invention automatically provides two separate scavenging stages, which together ensure the 0 any liquid condensate 1n the cylinders of complete remova the diesel engine before it can cause damage. It should be understood that the described and disclosed embodiment is merely exemplary of the invention and that all modifications are intended to be included that do not depart from the spirit of the invention and the scope of the appended claims.

lclaim:

l. A pneumatic starting system for a diesel engine cranked by an air-operated starter motor, comprising fluid-actuated valve means, a normally closed starter valve between and on opening connecting said valve means and a source of fluid pressure, said valve means on opening of said starter valve being automatically operative for applying operating air at operating pressure to said starter motor in a single initial cranking stage and a single final cranking stage time-separated by a dwell stage, and time delay means for predetermining the lengths of said initial cranking and dwell stages and thereafter causing said final cranking stage to continue uninterruptedly so long as said starter valve is open, whereby said diesel engine in starting is purged without damage of liquid condensate collected therein during an immediately preceding idle period.

2. A pneumatic starting system according to claim I, wherein the valve means includes normally open control and pilot valves, said control valve controlling by closing and reopening application of the operating air to the starter motor, and said pilot valve controlling said closing and reopening of said control valve.

3. A pneumatic starting system according to claim 2, wherein the normally closed starter valve is in a common supply line between the control and pilot valves and the source of compressed air.

4. A pneumatic starting system according to claim 3, wherein each of the control and pilot valves includes a differential piston for alternately opening and closing an outlet port to an inlet port thereof, said piston having an actuating head presented for actuation to actuating air introduced into a pressure chamber through an actuating air line.

5. A pneumatic starting system according to claim 4, wherein the actuating air line for the control valve connects to the outlet port of the pilot valve, the actuating air line for the pilot valve is open to the supply line between the starter and the control and pilot valves, and the time delay means are a pair of adjustable needle valves each in one of the actuating air lines.

6. A pneumatic starting system according to claim 5, wherein operating air is applied to the air motor through a normally closed fluid-actuated valve to an actuating side whereof the outlet port of the control valve is connected.

7. A pneumatic starting system according to claim 6, wherein each of the control and pilot valves has an exhaust port to which the outlet port thereof is alternately connected for bleeding actuating air respectively from the normally open valve and the control valve.

8. A pneumatic starting system according to claim 5, wherein the control and pilot valves, actuating air lines and needle valves are mounted as a unitary structure in a common valve body. 

1. A pneumatic starting system for a diesel engine cranked by an air-operated starter motor, comprising fluid-actuated valve means, a normally closed starter valve between and on opening connecting said valve means and a source of fluid pressure, said valve means on opening of said starter valve being automatically operative for applying operating air at operating pressure to said starter motor in a single initial cranking stage and a single final cranking stage time-separated by a dwell stage, and time delay means for predetermining the lengths of said initial cranking and dwell stages and thereafter causing said final cranking stage to continue uninterruptedly so long as said starter valve is open, whereby said diesel engine in starting is purged without damage of liquid condensate collected therein during an immediately preceding idle period.
 2. A pneumatic starting system according to claim 1, wherein the valve means includes normally open control and pilot valves, said control valve controlling by closing and reopening application of the operating air to the starter motor, and said pilot valve controlling said closing and reopening of said control valve.
 3. A pneumatic starting system according to claim 2, wherein the normally closed starter valve is in a common supply line between the control and pilot valves and the source of compressed air.
 4. A pneumatic starting system according to claim 3, wherein each of the control and pilot valves includes a differential piston for alternately opening and closing an outlet port to an inlet port thereof, said piston having an actuating head presented for actuation to actuating air introduced into a pressure chamber through an actuating air line.
 5. A pneumatic starting system according to claim 4, wherein the actuating air line for the control valve connects to the outlet port of the piloT valve, the actuating air line for the pilot valve is open to the supply line between the starter and the control and pilot valves, and the time delay means are a pair of adjustable needle valves each in one of the actuating air lines.
 6. A pneumatic starting system according to claim 5, wherein operating air is applied to the air motor through a normally closed fluid-actuated valve to an actuating side whereof the outlet port of the control valve is connected.
 7. A pneumatic starting system according to claim 6, wherein each of the control and pilot valves has an exhaust port to which the outlet port thereof is alternately connected for bleeding actuating air respectively from the normally open valve and the control valve.
 8. A pneumatic starting system according to claim 5, wherein the control and pilot valves, actuating air lines and needle valves are mounted as a unitary structure in a common valve body. 